King Leopold II of Belgium established the Congo Free State in 1885. The state was to be his own private possession, independent of the Belgian government, and Leopold justified it on humanitarian grounds. Given the brutal history of colonial rule in the Congo, such justifications tend to be regarded skeptically today, but there is no doubt that life in the Congo before Leopold gained control of it was hard and dangerous. Whether it was any less so afterwards is debatable, since it is certainly true that Leopold introduced new dangers and hardships.
The evidence concerning life in the Congo before 1885 is sketchy, and much of it comes from European colonists. Books such as Henry Morton Stanley's Through the Dark Continent (1878) provide a Eurocentric perspective. Nonetheless, it is clear that the topography of the region did not allow for large-scale kingdoms. People lived in small provinces and villages governed by tribal chiefs, who engaged in frequent border disputes and precarious, short-lived alliances. Regular contact, whether hostile or diplomatic, rendered these communities more homogenous over time.
People in these villages lived barely above subsistence level and were vulnerable to attack from both colonists and slavers. Until 1885, slavers were a much more serious threat, and when they were well-organized and equipped, there was little the villagers could do to repel them. This situation may not have changed much in the Congo Free State, the administration and defense forces of which were always chronically understaffed.